In the food packaging sector, we can identify two main food preservation technologies: modified atmosphere preservation (MAP) and controlled atmosphere packaging and conservation (CAP and CAS).
The primary objective is to change the space around the food in order to extend its shelf-life, so its duration expressed in days.
The fundamental element is the role of carbon dioxide (CO2) as a preservative. In fact, it is known since the last century that this gas has positive effects on the extension of the shelf life of many food products. Here is the reason why the air present in the atmosphere of the packaging is modified.
The most used gases are three: carbon dioxide, nitrogen and oxygen in different combinations and concentrations.
An important aspect to consider is the inhibition effect on micro-organisms naturally present on foods, due to the increase in the concentration of CO2. In fact, the activity of inhibiting the growth of CO2 microorganisms increases with decreasing storage temperature. This phenomenon occurs because carbon dioxide is more soluble in water at low temperatures.
In general, the modified atmospheres delay the development of the microbial growth cycle for the main bacteria that affect food.
Another important advantage of the modified atmosphere storage is the “dilution” of the air residues present in the package; even if the food is vacuum packed, a small quantity of air remains in the package, since the absolute vacuum cannot be reached. In the packaging atmosphere there is this small amount of air that represents the total gas present. With the introduction of the mixed gases typical of MAP technique, the amount of residual air must therefore be “diluted”, thus improving the conservation performance. It is like saying that from a 100% of initial air, depending on how much other gases such as carbon dioxide, oxygen and nitrogen are introduced, the air is reduced. This creates very optimum conditions for the storage.
Therefore, a carefully controlled MAP preserves the color, taste and nutritional properties of various foods, extending their shelf-time.
Below we present an example table of the possible combinations of gases for food storage in modified atmosphere.